Electric ignition apparatus



April 21, 1931. 'r. L. LEE 1,801,608

7 I ELECTRIC IGNITION APPARATUS Filed March 19, 1929 Patented Apr. 21, 1931 UNITED STATES PATENT OFFICE THOMAS L. LEE, OF ROCHESTER, NEW YORK, ASSIGNQR, BY MESNE ASSIGNMENTS, TO

NORTH EAST APPLIANCE CORPORATION, OF 1R0GHESTZEITt Z S'ILTi YORK, A. CORPORA- TION OF NEW YORK ELECTRIC IGNITION APPARA'I'UiS This invention relates to ignition apparatus of the jump-spark type, and the-object of the invention is to produce a system which shall be capable of the high-speed operation required by modern automobile engines, without the necessity of overloading and burning the contacts of the primarycircuit breaker.

High-speed operation, in apparatus of the 10 kind in question, necessitates the use, in the primary winding of the ignition coil, of a relatively heavy current, to compensate for the short space of time during which the circuit can be closed. This requirement makes low contact resistance desirable, but the heavy current has a tendency to cause oxidation of the contacts of the circuit controller with the result of increasing the contact resistance and of destroying the contacts rapidly.

To reduce these undesirable eiiects it has been the practice, to some extent, to provide the circuit controller with two pairs of contacts, which are operated simultaneously, by

the same cam, and are connected in parallel so as to divide the current between them.

This arrangement tends to reduce the total contact resistance. It is not effective to prevent oxidation of the contacts, however, because it is impossible to adjust the mecha-. nism for absolutely simultaneous operation, and the interruption of the current is always performed chiefly by the pair of contacts which opens later.

In the apparatus of the present invention the equal division of the primary current, between two pairs of contacts, is insured by providing two distinct primary windings in the ignition coil or transformer, each of these windings being connected with its respective air of contacts. The secondary winding is in inductive relation with the two primary windings, so that they act cumulatively upon it, the eflect being substantially the same as if all the primary current passed through a single winding, except that the present arrangement absolutely insures that each pair of contacts shall have the duty of interrupting only one half of thetotal primary current.

In an arrangement such as just described, it is desirable to avoid magnetic coupling between the two parallel primary circuits. It is inevitable that one circuit will be opened slightly before the other, and if the two primary windings are arranged upon the same magnetic core, the result will be a transfer of energy from one circuit to the other, which trans erwill cause dissipation of energy and also enhance the tendency to arcing at the contacts. In accordance with the present invention, accordingly, each primary winding is provided with an independent iron core, and the two cores are separated as far as convenience in constructionwill permit, to minimhize magnetic influence of one core upon the ot er.

In theory it might seem that the distinct 7 primary windings and cores might also be provided with distinct secondary windings, so that there would be, in fact, two entirely separate coils or transformers, with their secondary windings connected in parallel or in series, Actually, this arrangement is not satisfactory. If the secondary windings be connected in parallel, the non-simultaneous operation of the primary contacts results in a diiierence in the potential of the two secondary windings, sothat there is an interchange of energy betweenthe two coils, first in one sense and then in the opposite sense,

whereby the energy'is largely dissipated, so that the arrangement is ineflicient. If the secondaries be connected in series, on the other hand, serious difficulties in insulation arise, owing to the fact'that portions of the windings which are at high potential will inevitably be in close proximity to the primary winding and the core, one or both of which are at, low potential or grounded. In accordance with the present invention, ac-

cordingly, the primary windings and the cores are combined with a secondary wound as a single helical coil in inductive relation with both magnetic cores.

In the accompanying drawings Fig. 1 is a diagram of an ignition system embodying the present invention. Fig. 2 is a dia ammatic longitudinal sectional view of t e ig-- 2 ism-cos nition coil, and Fig. 3 is a detail view of the secondary winding of the coil. i Fig. 1 shows the ignition apparatus as comprising a coil or transformer having two primary windings 5, 5 associated with their respective cores 6, 6. A single secondar winding 7 is associated with both cores.

battery 8 furnishes the electrical ener and the current through the primary win ngs is controlled by two contact-arms 9, 9, which are 0 erated, as nearly'simultaneously as possib e, by a single cam 10 in the usual manner. The high-tension current from the secondary winding 7 is controlled by the usual distributor,comprising a rotor 11 and electrodes 1 12, the electrodes being connected with the spark-plugs 13 (of which only one is shown) in the respective cylinders of the engine. The ignition coil used in the system of Fig. 1 is shown, in Fig. 2, as bein arranged with the primary windings outsi e the secondary winding. The cores 6 are separated by a suflicient air-gap to prevent any substantial amount of magnetic coupling, and the magnetic circuit ofeach primary is preferably improved by the addition of'iron 14 outside the windings. I

Since the secondary winding 7 .is wound as a single helical coil, it is obvious that those so turns lying in the air-space between the two magnetic circuits are practically dead, i. e. useless for the induction of electromotive force, and that they add undesirable resistance to the secondary circuit. The number and eflect of these intermediate turns may be minimized by changing the pitch of the middle part of each layer of the winding, so that this part consists of only a few turns, as shown at 15 in Fig. 3. 4o The invention claimed is:

An ignition coil for a divided primary ignition system, comprising in combination, a seconda coil having its layers 'so wound that an intermediate portion of each layer consists of turns of wire spaced apart a greater distance than other portions of the layer, separated magnetic cores each within the coil portion consisting of the closely spaced turns, separate primary coils eac surrounding a secondary coil portion consisting of the closely spaced turns, and separate magnetic tubular odies each surrounding a primary coil.

, THOMAsL. LEE. 

